The influence of H2O2 on the properties of CeO2-ZrO2 mixed oxides

Abstract

A series of ceria-zirconia (CZ) mixed oxides were prepared by coprecipitation, in which different amounts of H2O2 were added to investigate the influence of H2O2 on the properties of CZ. Modifications in structure, oxygen storage capacity, reducibility and thermal stability were studied systematically. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results revealed that the thermal stability of the material was dramatically improved by the addition of H2O2, which was mainly due to the increase of the solubility of ZrO2 in ceria from 4.7 to 69.3%. The study of UV Raman spectroscopy confirmed that the concentration of defect sites of CZ materials increased with increasing H2O2/Ce molar ratio. The material prepared with H2O2/Ce molar ratio of 2 (CZ-2) exhibited the highest structural stability, the solubility of which was 68.8 and 69.3% before and after thermal treatment, and it maintained a homogeneous single cubic phase even after aging treatment at 1000 °C for 3 h. Also the highest thermal stability of the oxygen storage capacity (OSC) was found in CZ-2, which showed the reduction rates of 80.4 and 76.4% before and after thermal treatment. Moreover, a reaction mechanism of H2O2 and metal ions in the mixed precursor solution was assumed, in which the cerium-peroxide bridge-zirconium complex structure was proposed.